Numerous techniques have hitherto been proposed in which methods of winding coil wires as well as structures of windings wound on stator cores, in order to improve efficiency of winding work and space factors of the windings inside slots of motor stators of such a type that is driven by a three-phase power supply (refer to Patent Literature 1, for example).
Patent Literature 1 provides an improvement of a connecting structure of neutral wires to form a neutral point of the three-phase Y-connection, and simplifies the connection of windings in a stator. That is, in the stator having a plurality of magnetic polar teeth along the circumferential direction, neutral wires of coils of any two phases among the three phases are connected individually to a neutral wire of the other phase coil at their respective positions. This helps form a neutral point by connecting a reduced number of the neutral wires, and simplifies the wire connections.
According to the technique disclosed in Patent Literature 1, however, the winding and wiring process, including the above-described step of connecting the neutral wires needs to be carried out on a stator core having magnetic polar teeth disposed in an annular shape. In other words, it requires a task of complicated wiring work in the wiring step of the windings of the stator assembly in order to complete the winding and wiring process of the annularly-shaped stator core, and it hence gives rise to a problem of not being able to achieve a sufficient degree of simplification in the winding and wiring process including the process of connecting the neutral wires.